According to our current understanding of physics, an object with mass cannot reach or exceed the speed of light in a vacuum. As an object with mass accelerates, its energy and momentum increase, making it more and more difficult to continue accelerating. As the object approaches the speed of light, its mass effectively increases, requiring an infinite amount of energy to reach the speed of light. Therefore, it is not possible for a spaceship with mass to reach or exceed the speed of light.
However, let's consider a hypothetical scenario where a spaceship could approach but not exceed the speed of light. In this case, the spaceship would experience significant time dilation and length contraction effects as predicted by Einstein's theory of relativity. As the spaceship accelerates, time would pass more slowly for the occupants of the ship compared to an outside observer.
If the spaceship were able to maintain constant acceleration, the occupants would experience time dilation and the journey would appear shorter from their perspective. However, from an observer's viewpoint, the spaceship would continue to approach but never reach the speed of light.
As for entering another universe, the concept of "another universe" is not well-defined in the context of our current scientific understanding. The idea of traveling to another universe typically belongs to the realm of speculative theories, such as those found in science fiction. The hypothetical ability to travel to another universe would depend on the specific nature and properties of that universe, which are not known or understood with certainty at present.